Low-pressure alarm for vehicle tires



I. L. SINCLAIR ET AL LOW PRESSURE ALARM FOR VEHICLE TIRES Sept. 14 1926.

Filed Oct. 23; 1925 Cubans Patented Sept. 14, 1926.

UNITED STATES a v I 1,599,846 PATENT OFFICE.

ISAAC L. smcmun am) ronnnsr J. SINCLAIR," or swarm, onmon.

row-ranssunn ALARM son VEHICLE Tums;

Application filed October 23, 1925. Serial No. 64,402."

alarm being entirely automatic inits nature and of such simpleconstruction as to operate properly and efiiciently under allconditions.

The primary object of the invention is to substantially improve andsimplify previolulsly patented devices for obtaining this res t.

An additional object of the invention is to provide an alarm thatcomprises means associated with each articular vehicle wheel and tirefor automatically completing a circuit to an indicator that ispreferably arranged upon the instrument board of the Vehicle in orderthat the operator will readily recognize the indicator when the same isin operation..

A.v further and important object is to provide means whereby themechanism may be said to operate at various'low pressures of the tires,e

Other ob'ectsiwill become apparent as the nature of t e invention isbetter understood from the following specification considered inconjunction with the accompanying drawings.

In the drawing wherein like reference characters designate correspondingparts throughout both the views Figure 1 is an'inside yiew of a vehiclefront wheel, portions of its complementary supporting mechanism beingshown in cross section, and with which is associated the mechanicalelements of the present invention,

which are shown partly in elevation and partly in section, of theindicating, means per se'which is of an electrical nature, being shownin diagram, and

Fig. 2 is an enlarged detail section through the tire pressure controlconstruction of the present invention.

'In the drawing, we have shown our automatic pressure alarm as beingassociated with one of the front wheels of a vehicle, it neverthelessbeingunderstood that through minor changes the device may be associatedwith the rear wheels and in fact it is to be understood that themechanism of the eneral character as herein shown and described isto beassociated with each of the wheels of a vehicle in order that an alarmwill be sounded when the pressure in the tires of the four wheels lowlevel. I

In the drawings, 5 is a conventional form reaches a predetermined ofvehicle wheel with which is associated the usual pneumatic tire 6, thetube of which carries the usual air inflating valve that comprises athreaded stem 7 in which is the valve mechanism 8, Fig. 2. 1

As is well known, the wheel 5 is mounted for rotation upon the usual. sindle of a spindle body 9 that is mounted etween the forked ends 1010 ofthe usual axle, not shown.-

Our invention, per se, constitutes the provision of an electricalconducting ring 11' that -'is bolted or otherwise suitably secured tothe spokes of the wheel 5 in concentric relation with the hub thereofand upon the interior side of the said wheel. tion with the rear. end ofthe usual spindle arm 12 of the wheel steering mechanism and insulatedtherefrom is a twoart clamp 13-, to the upper section-of whic ispivotally mounted a bell crank 14, the inner arm of which carries anelectrical contact roller 15 that is maintained in rollin contact withthe ring ,11 through the me ium of a con- 'the spindlearm 12 forwardlyof the first mentioned clamp. 13.

Our'alarm further includes an air receiving bulb 17' that is ofcollapsible non stretchable material that is air impervious such asrubberized fabric or the like. bulb 17 is formed with an air inletnipple 18, which has partially disposed therein in an airtight manner, ametal cap 19, the open end of which is internally threaded for threadedrelation with the tire valve stein 7. This cap 19 is formed internallywith a cross web 20 dependent from thecenterof which is a pin 21 thatengages the usual valve stem of the valve mechanism within the stem 7when the cap 19 is threaded thereon for obviously releasing the valveand for allowing the air toenter the bulb 17.

In diametrically opposed relation with the nipple 18, is a ni p le 22through which extends the eye en of a relatively thin eyebolt 23, thethreadedend of which is i ed In associa- Said that is secured to anadjacent spoke of the wheel 5.

At this point it may be well to note that the cap 19 and eyebolt 23 maybe secured within the nipples of the bulb through the medium of cementor the like to prevent the passage of the air between the walls of thenipple and said cap and eyebolt, and further that the top wall of saidcap is provided witha plurality of openings to enable the air from thetire to pass into the bulb 17 which is necessary to the successfuloperation of the device.

Mounted for threaded adjustment in the bolt 23 at its outer end is anelectric contact member 25, while normally maintaining the bulb 17' flatand consequently the member 25 in contact with the member 24 is acontractile coiled spring 26 within said bulb and secured at itsopposite ends to the eyed end of the bolt and the cap 23 and 19respectively. Obviously, the pressure within the tire 6 is normally suchas to expand the bulb 17 which will force the eyebolt outwardly throughthe opening the bracket 24 for maintaining the contact member 25 out ofengagement therewith.

Our improved alarm further constitutes the provision of an electric bulb27 that is preferably mounted upon the instrument board of the vehicleand that has electrical connection at one point as at a with one pole ofthe vehicle storage battery X and at its other points with the upperfinger of the axle fork 10 as at 6, within which connection'may bedisposed a conventional switch 0.

The other battery has electrical connection as at d with'the bell crank14, while the contact bracket 24 has electrical connection as at e withthe contact ring 11 and in addition thereto, the contact member 25 iselectrically connected with a metal portion of the wheel 5 as at d whichmetal portion through other metallic elements of the wheel, spindlebody, axle and the like, is in continuous circuit with the vehicle axlewhich is electrically connected to the bulb 27 as previously mentionedat b.

The operation of the device will be readily apparent bulb 17 will beinflated and consequently the contacts 24 and 25 will be out ofengagement. During the reduction of pressure within the tire the spring26 will tend to collapse the bulb 17 and at a certain low pressure thecontacts 24; and 25 will be brought into engagement for completing thecircuit to the bulb 27 when the switch 0 is closed at which time thebulb will become illuminated for readily indicating to the operator thatthe particular tire of the vehicle is at a lower pressure and needsimmediate attention. The re-inflation of the tire will inflate the bulb17 and so move the bolt 23 as to disengage the contact 25 from thecontact bracket 24.

Minor changes may be made in the invention without departing from thespirit and scope of the appended claim.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent is 2-- A circuit making and breaking deviceadapted for use in connection with the air valve of a pneumatic tire,said device comprising a collapsible air receiving bag, a cap arrangedin the bottom of the bag and being adapted to be threaded on the upperend of the threaded valve stem of the pneumatic tire, the top of saidcap being provided with openings whereby communication between the airvalve and the bag is provided, a depending pin carried by the cap andadapted for engagement with the valve stem whereby the latter is helddepressed to permit the air to escape from the. tire into said bag, astationary contact su ported in spaced relation with respect to the topof said bag, a coacting contact extending through the top of the bag,and a contractile coil spring arranged within the bag and secured at itsopposite ends to the cap and the contact respectivelygsaid contactsbeingnormally held in an inoperative position and the contractile' coilspring expanded, the contacts being adapted to be disposed in anoperative posi tion when the air pressure inthe bag reaches apredetermined level, and the bag is collapsed by the action of the coilspring.

In testimony whereof we affix our signatures. v

ISAAC L. SINCLAIR. FORREST J. SINCLAIR.

